[M13 reverse] Reconstruct the declared Workshop surface as valid OSTW source

[Teakowa]

Parent: #90
Depends on: #119

Goal

Implement Wright-owned Workshop -> OSTW source reconstruction for a declared, evidence-backed Workshop/WIR surface, producing canonical useful OSTW that recompiles to semantically equivalent Workshop.

Context

Raw Workshop already parses into validated Wright WIR, and the accepted native OSTW frontend compiles its declared surface back through the same shared WIR/Workshop semantics. Reverse reconstruction should therefore consume canonical WIR directly and emit simple valid OSTW, not attempt to recover lost high-level source abstractions.

Scope

• Add an OSTW-owned reconstruction/emission API that consumes validated Wright WIR.
• Emit deterministic canonical OSTW for the subset supported by the native wright-ostw frontend and the pinned semantic/reference evidence.
• Cover the core structured Workshop surface representable by current OSTW semantics: variables/indices, subroutines or equivalent rule structure where representable, rules/events/conditions, scalar/array/vector/enum values, variable access, actions/values, assignment/modify operations, if, while, and representable loop forms.
• Use the canonical Workshop catalog and existing OSTW source bindings for action/value/enum names; do not create duplicate Workshop metadata.
• Prefer low-level valid OSTW structure over speculative recovery of classes, functions, macros, project abstractions, or library APIs.
• Explicitly reject WIR constructs that cannot currently be represented by the declared OSTW source/frontend surface.
• Validate with the full loop:
  Workshop -> WIR -> OSTW source -> native OSTW frontend -> WIR -> Workshop, comparing observable/normalized semantics.
• Where useful and legal, additionally validate generated source against the pinned OSTW v3.4.0 oracle, but keep the upstream runtime reference-only.
• Add deterministic fixtures and a machine-readable reconstruction support boundary.

Non-goals

• Recovering original OSTW formatting/comments/classes/macros/functions/import graph/project structure.
• Copying upstream OSTW compiler/data or adding an upstream runtime dependency.
• Inventing Wright-only OSTW syntax.
• Whole-source regeneration for agent edits.
• Workshop -> OPY; tracked separately.
• Adding the shared CLI conversion command; final integration follows both reconstructors.

Acceptance criteria

• A library consumer can reconstruct valid canonical OSTW from every WIR construct declared supported by this issue.
• Reconstructed OSTW is accepted by Wright's native OSTW frontend without upstream runtime support.
• Recompiling reconstructed OSTW produces Workshop semantically equivalent to the original under Wright's declared normalization/round-trip contract.
• Unsupported constructs fail explicitly rather than producing misleading or reference-incompatible source.
• Workshop metadata remains owned by the canonical catalog; OSTW keeps only source-language binding/presentation logic.
• Current OPY/Workshop/OSTW compatibility and CI gates remain green.

Relationships

• Reverse-interoperability child of [M13] Source-language interoperability and OSTW compatibility #90 after [M13] Compile the accepted OSTW corpus slice to Workshop with reference differential validation #119.
• May proceed in parallel with Workshop -> OPY reconstruction.
• Enables final shared conversion/CLI integration and M13 acceptance.

[Teakowa]

Acceptance evidence — Workshop → WIR → OSTW reconstruction (#125)

Commit: 896edf0 (feat(ostw): reconstruct validated Workshop IR as deterministic OSTW (#125)), pushed to main. Full GitHub Actions suite green on the pushed commit (all jobs: Rust quality on stable and 1.85.0, v1 gates, compatibility oracle, OSTW reference, OSTW compile differential, adapter, compatibility differential, dist validation).

What shipped

• crates/wright-ostw/src/reconstruct.rs — the OSTW-owned reconstruction API: wright_ostw::reconstruct::reconstruct(program, catalog) -> Result<String, Vec<ReconstructError>>. A validated wir::Program whose constructs lie on the declared surface is converted into deterministic canonical OSTW; a total classification pre-pass collects every structured rejection first, so no partial or misleading source is ever produced.
• compatibility/ostw/reconstruction/ — deterministic fixtures (3 positive Workshop sources, 1 rejection source) plus the machine-readable support-boundary.json manifest whose supported/rejected sets exactly match the fixtures and the shipped classification API (enforced by the boundary-conformance test).
• crates/wright-ostw/tests/reconstruct.rs — the full-loop integration suite and unit tests: per-construct emission, double-emission byte-identity, structured-rejection coverage for every declared boundary kind, reverse-binding table checks, and manifest ↔ classifier ↔ fixture-coverage conformance.
• docs/ostw/support-matrix.md — the declared reconstruction surface and boundary section.

Acceptance-criteria mapping

1. Library API converts the declared surface to canonical OSTW — variables (globalvar Any/playervar Any), rules/events/conditions, subroutines, scalar/array/vector/enum values, variable access, actions/values, assignment/modify operations (incl. .append), if, while, and for forms. Identical WIR always yields byte-identical output (determinism test). Source names reverse the existing signature.rs bindings and resolve through the canonical catalog; arithmetic emits as the real OSTW infix operators + - * / (callable Add(...) forms are rejected by the pinned reference and are never emitted).
2. Native-frontend acceptance, zero diagnostics — every reconstructed fixture loads through wright_ostw::compile_with_semantics in a generated ds.toml project root with zero project/parse/semantic diagnostics; target/wright-ostw-reconstruct-report.json records status: round-trip / frontend: wright/ostw-native zero diagnostics per fixture.
3. Full loop holds — for every fixture, Workshop → WIR → OSTW → native frontend → HIR → WIR → Workshop is proven: both sides normalize under the declared [M13] Compile the accepted OSTW corpus slice to Workshop with reference differential validation #119 normalization, the structural comparison passes, and the reconstructed Workshop text reparses and re-emits byte-identically (round-trip fixed point).
4. Explicit rejection, no partial output — ForPlayerVariable, debug, print, Program.settings, unbound action/value calls, unbound enum domains, Raise To Power/Remove From Array modify ops, non-comparison conditions, partial-arity bound calls, name collisions, bodiless subroutines, non-literal format strings, and invalid number spellings all fail with structured, deterministic diagnostics; every kind in support-boundary.json is covered by a rejection test.
5. Existing gates stay green, evidence left on the issue — see validation below.

Validation (local, matching CI)

• cargo fmt --all -- --check, cargo clippy --workspace --all-targets --all-features -- -D warnings, cargo test --workspace --all-targets --all-features (53 test binaries, 0 failures), cargo test -p wright-ostw --test differential, cargo test -p wright-opy --test differential, python3 -m unittest discover -s compatibility/tests (18 tests), python3 scripts/v1-gates.py (6/6), python3 scripts/run-scenarios.py (7/7).
• Optional pinned-OSTW v3.4.0 cross-check ran (Docker): the reconstructed surface-basic project compiles reference-clean except the documented .append(value) divergence — the pinned reference rejects member-call methods while Wright's native frontend accepts them (declared divergence; reference-only by contract, not an acceptance barrier).

Artifacts

• target/wright-ostw-reconstruct-report.json (repo report pattern, produced by the CI-protected suite).
• Fixtures + manifest: compatibility/ostw/reconstruction/ (support-boundary.json, surface-*, reject/).
• Suite: crates/wright-ostw/tests/reconstruct.rs.